>>2350310you can't suck air down a tube at depths, because of the pressure difference.
the air has to be pumped down the tube.
You can buy such devices, picrel.
I wouldn't recommend it though. this is an incredibly dangerous way to dive and there is a huge amount that could go wrong.
You should just learn freediving/spearfishing. Most people can learn to freedive to 10-15m with minimal tuition.